Medium-depth geothermal an energy option for Luxembourg

Medium-depth geothermal an energy option for Luxembourg Abbey Neumunster, Luxembourg City (source: flickr/ Gabi Agu, creative commons)
Alexander Richter 28 Jul 2021

While shallow geothermal is seen as important for Luxembourg's clean heating/ cooling plans, medium-depth geothermal in the South could be a real option.

Currently, thousands households in the Grand Duchy of  Luxembourg have a heating / cooling system linked to heat pumps drawing their energy from the subsurface. But there is development potential, particularly in the south of Luxembourg, so local publication Luxemburger Wort.

Luxembourg is a small landlocked country bordering Belgium, bordered by Belgium, France and Germany, mostly known for its financial market.

Of course, this is a renewable energy resource that is still far from competing with solar or wind power. But at the time of environmental commitments , do not count on Claude Turmes (Déi Gréng) to neglect the track of geothermal energy. The Minister of Energy said for the country an achievable potential of 180 Gigawatts / hour per year remains perfectly possible in combination with the installation of heat pumps for a technique used at shallow depth.

Green electricity is not just wind

For the time being, the country is still far from having converted to this method of producing heat or fresh air, drawing its efficiency from the heat stored under our feet . Thus, deep geothermal energy (2,500 meters below the surface) makes it possible to produce electricity (via the vapors extracted at 150-250 °C). Average geothermal energy (30 to 150 °C) is effective in supplying urban heating networks. When very low energy geothermal energy (between 10 and 100 meters deep and less than 30 °C) is generally exploited by heat pumps installed by individuals.

To cover the 12,873 GWh / year of energy needed to heat the entire country, this low-carbon production will have to be boosted. “Between 2015 and 2020, 727 authorizations to carry out boreholes for the use of shallow geothermal energy were granted,” says the environmental minister. But we must accelerate beyond this rate of 125 annual authorizations.

The boost

Until December 31, 2021, the State has chosen to increase its support for individuals abandoning their boiler fueled with fossil energy (oil or gas) for a renewable and more ecological alternative (such as geothermal energy). Thus, the bonus granted is inflated by 30% to help with this conversion.

“In 2019, the installed capacity of geothermal heat pumps was 6.07 MW and the estimated production was 11.13 GWh. In terms of percentages in relation to the total consumption of the heating / cooling sector, this is indeed a very low rate (1%) but which nevertheless corresponds to the supply of some 1,000 households with renewable heat ”, not fail to underline the Minister of Energy.

And if Claude Turmes is optimistic it is that in Luxembourg, an interesting potential in medium-depth geothermal energy is “probably located in the south of the country”. The former mining area could thus turn into a golden triangle of geothermal energy, between Esch-sur-Alzette, Bettembourg and Dudelange.

As proof, the first underground soundings that were made, at medium depth, in particular to ensure the heating of future homes in the new Neischmelz (Dudelange), Lentilles Rouges in Esch or near the future Mondorf-les-Bains velodrome . Other exploitation projects are also pointing towards Roeser or Kayl.

However, there is no question of moving too fast on the question. Thus, each time, a feasibility study is necessary. Both to assess the impact of the well on the water table, but also on the reaction of the soils to this new hydraulic circulation. A sign that the question of water is moreover well taken into account, Claude Turmes recalls moreover that the realization of geothermal wells is “prohibited in the zones of protection around catchments intended for human consumption”.

Beware of seismicity

A limit on digging has also been set in certain regions, including the south, to avoid any disturbing ground movement. In the style of the earthquakes that have shaken the Alsatian capital, Strasbourg, since an installation came into service in its outskirts.

The Water Management Administration as well as the Ponts et Chaussées (geological service) thus remain vigilant to any new project. It is up to them to carry out the environmental impact assessments of this virtuous practice if it is properly implemented.

Source: Luxemburger Wort